THE IMPACT OF RENAL DENERVATION ON THE BAROREFLEX CONTROL OF HEART RATE IN AN EXPERIMENTAL MODEL OF REDUCED RENAL MASS, SALT SENSITIVE HYPERTENSION

Background. Beyond lowering arterial blood pressure in hypertensive patients, renal denervation (RDNx) has also been shown to improve the cardiac autonomic nervous system, particularly in sympathetically mediated cardiovascular disorders. Nevertheless, little is known about the efficiency of renal nerve ablation in non-mediated sympathetically diseases. Therefore, our aim was to investigate the influence of renal denervation on the cardiac autonomic nervous system in an experimental rat model of salt sensitive, volume-overload hypertension developed after surgical reduction of renal mass (RRM) by 75-80% and salt loading. Material and methods: The dynamic time-dependent cardiac autonomic system analyses such as the baroreflex sensitivity (BRS), the power of the fluctuations of the heart rate in high frequency range (0.75-3Hz, HF power) and both short and long-term beat-to-beat variability were calculated from continuously recorded cardiac cycles before and after surgical RRM by 80%, including here RDNx and central sympathoinhibition with clonidine. Results: The BRS decreased significantly throughout the entire 2 weeks of the development of salt-sensitive, volume overload hypertension induced after surgical RRM and high salt diet. After RDNx, the HF power decreased during the first 7 days, paralleling the alterations of both long and short-term heart rate variability. Global sympathoinhibition after clonidine administration significantly improved the cardiac autonomic nervous system as reflected by the substantial enhancement of the BRS, the HF power and both short and long-term heart rate variability. Conclusions: The present results indicate that in salt-sensitive, volume overload hypertension, the cardiac autonomic nervous system is impaired, and these alterations are not improved over the long term by RDNx. On contrary, central sympathoinhibition after clonidine administration following RDNx significantly improved BRS, the HF power and both short-and long-term beat-to-beat variability.